The primary goal of this research project is to investigate the development of the geniculate-cortical pathways in the cat. First, we plan to study the patterns of axon arborization by using anterograde filling of individual dorsal lateral geniculate (LGN) efferent fibers with horseradish peroxidase (HRP) either by larger HRP injections or by single fiber (classified as X- or Y-fibers) recording followed by injection with HRP. The above techniques will be used in the young kittens and adult cats. Secondly, we will correlate individual axonal arborization patterns with ocular dominance columns using a combination of HRP with transneuronal autoradiographic methods to identify the precise relationships. Finally, we will use the same approaches to study the effects of suturing on one eye lid, convergent squint, and unilateral enucleation on the geniculate-cortical pathways of those kittens. We hope that knowledge gained from these studies will provide us with a rather precise functional picture of neuronal development and neuroplasticity.